14348( 5) - 29-Jul-2015 14:19:13 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14348 Version: 5 Check-in Time: 29-Jul-2015 14:19:13 STScI Edit Number: 1 Title Polarimetry of ASASSN-15lh as a probe of explosion physics of the most luminous supernova ever discovered ------------------------------------------------------------------------------------ Type Cycle GO/DD 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Mr. Yi Yang Texas A & M University Y CoI: Dr. Dietrich Baade European Southern Observatory - Germany N CoI: Dr. Peter J. Brown Texas A & M University N CoI: Dr. Jeff Cooke Swinburne University of Technology N CoI: Dr. Peter A. Hoeflich Florida State University N CoI: Dr. Justyn Maund University of Sheffield N CoI: Dr. Jeremy R. Mould Swinburne University of Technology N CoI: Dr. Ferdinando Patat European Southern Observatory - Germany N CoI: Dr. William B. Sparks Space Telescope Science Institute N CoI: Dr. Lifan Wang Texas A & M University Y CoI: Dr. J. Craig Wheeler University of Texas at Austin N ------------------------------------------------------------------------------------ Abstract Barring any viewing-angle dependencies, ASASSN-2015lh is the most superluminous supernova (SLSN) ever observed. An important key to the understanding of any type of object is its shape. At redshift 0.23, this rare event is still within reach of the imaging polarimetric capabilities of HST, even at relatively late epochs. Linear continuum polarization measured to 0.5% will yield deviations from sphericity at the 5% level. Observations at multiple epochs will probe the disintegrating star at increasing geometric depth and ultimately enable causal physical processes such as massive-star core-collapse and disruption of a star by a black hole to be decisively tensioned against each other. Interstellar foreground polarization can be subtracted as the remaining signal after the light curve has faded to the background level. Any polarization by circumstellar matter can be identified by its dependency on wavelength, time, and angle and may contribute critical information about the progenitor and late phases of its evolution. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program attempts to acquire imaging polarization of ASASSN-2015lh using ACS/WFC. We intend to observe at one epoch at around early August 2015. The polarization data will be observed in three filters: F435W, F606W, and F775W. For F606W and F775W, each filter three polarizers POL0V, POL120V, and POL60V are used to aqcuire a complete polarization data set. For F435W, the POLOUV, POL120UV, AND POL60UV will be used. Multiple exposures are required for cosmic ray rejection. CALIBRATION ORBITS: As per STScI policy, 4 internal orbits have been added to this proposal for the purpose of obtaining subarray bias frames that are contemporaneous with the science observations. These internal orbits will be charged to STScI's Cycle 22 ACS Calibration Program, not to 14348( 5) - 29-Jul-2015 14:19:13 - [ 2] GO 14348. The ACS Instrument Team at STScI is responsible for producing superbias reference files from the bias frames obtained in this GO proposal. ------------------------------------------------------------------------------------ 14348( 5) - 29-Jul-2015 14:19:13 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ASASSN-2015L STAR, SUPERNOVA RA=22H02M15.4500S +/- 0.5", J2000 V = 18.0 +/- 0.5 H DEC=-61D39'34.64" +/- 0.5" Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14348( 5) - 29-Jul-2015 14:19:13 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 14348( 5) - 29-Jul-2015 14:19:13 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ASASSN-2015 ACS/WFC ACCUM WFC1 F606W, 1 122 S (366 PATTERN 1 1 LH POL0V S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ASASSN-2015 ACS/WFC ACCUM WFC1 F606W, 1 122 S (366 PATTERN 1 2 LH POL120V S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ASASSN-2015 ACS/WFC ACCUM WFC1 F606W, 1 122 S (366 PATTERN 1 3 LH POL60V S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ASASSN-2015 ACS/WFC ACCUM WFC1 F435W, 1 138 S (414 PATTERN 1 4 LH POL0UV S) ------------------------------------------------------------------------------------------------------------------------------------ 5 ASASSN-2015 ACS/WFC ACCUM WFC1 F435W, 1 138 S (414 PATTERN 1 5 LH POL120UV S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ASASSN-2015 ACS/WFC ACCUM WFC1 F435W, 1 138 S (414 PATTERN 1 6 LH POL60UV S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ASASSN-2015 ACS/WFC ACCUM WFC1 F775W, 1 137 S (411 PATTERN 1 7 LH POL0V S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ASASSN-2015 ACS/WFC ACCUM WFC1 F775W, 1 137 S (411 PATTERN 1 8 LH POL120V S) ------------------------------------------------------------------------------------------------------------------------------------ 9 ASASSN-2015 ACS/WFC ACCUM WFC1 F775W, 1 137 S (411 PATTERN 1 9 LH POL60V S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-2015LH 1 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL0V ASASSN-2015LH 1 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL0V ASASSN-2015LH 1 ACS/WFC ACCUM WFC1 F606W, 3 none none none 1 N/A POL0V ASASSN-2015LH 2 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL120V 14348( 5) - 29-Jul-2015 14:19:13 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-2015LH 2 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL120V ASASSN-2015LH 2 ACS/WFC ACCUM WFC1 F606W, 3 none none none 1 N/A POL120V ASASSN-2015LH 3 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL60V ASASSN-2015LH 3 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL60V ASASSN-2015LH 3 ACS/WFC ACCUM WFC1 F606W, 3 none none none 1 N/A POL60V ASASSN-2015LH 4 ACS/WFC ACCUM WFC1 F435W, 1 none none none 2 N/A POL0UV ASASSN-2015LH 4 ACS/WFC ACCUM WFC1 F435W, 2 none none none 2 N/A POL0UV ASASSN-2015LH 4 ACS/WFC ACCUM WFC1 F435W, 3 none none none 2 N/A POL0UV ASASSN-2015LH 5 ACS/WFC ACCUM WFC1 F435W, 1 none none none 2 N/A POL120UV ASASSN-2015LH 5 ACS/WFC ACCUM WFC1 F435W, 2 none none none 2 N/A POL120UV ASASSN-2015LH 5 ACS/WFC ACCUM WFC1 F435W, 3 none none none 2 N/A POL120UV ASASSN-2015LH 6 ACS/WFC ACCUM WFC1 F435W, 1 none none none 2 N/A POL60UV ASASSN-2015LH 6 ACS/WFC ACCUM WFC1 F435W, 2 none none none 2 N/A POL60UV ASASSN-2015LH 6 ACS/WFC ACCUM WFC1 F435W, 3 none none none 2 N/A POL60UV ASASSN-2015LH 7 ACS/WFC ACCUM WFC1 F775W, 1 none none none 3 N/A POL0V ASASSN-2015LH 7 ACS/WFC ACCUM WFC1 F775W, 2 none none none 3 N/A POL0V ASASSN-2015LH 7 ACS/WFC ACCUM WFC1 F775W, 3 none none none 3 N/A POL0V ASASSN-2015LH 8 ACS/WFC ACCUM WFC1 F775W, 1 none none none 3 N/A POL120V ASASSN-2015LH 8 ACS/WFC ACCUM WFC1 F775W, 2 none none none 3 N/A POL120V ASASSN-2015LH 8 ACS/WFC ACCUM WFC1 F775W, 3 none none none 3 N/A POL120V ASASSN-2015LH 9 ACS/WFC ACCUM WFC1 F775W, 1 none none none 3 N/A POL60V ASASSN-2015LH 9 ACS/WFC ACCUM WFC1 F775W, 2 none none none 3 N/A POL60V ASASSN-2015LH 9 ACS/WFC ACCUM WFC1 F775W, 3 none none none 3 N/A POL60V 14348( 5) - 29-Jul-2015 14:19:13 - [ 7] Visit: A1 Visit Requirements: SEQ A1, A2, A3, A4 WITHIN 1 D On Hold Comments: Additional Comments: This internal orbit will be charged to the Cycle 22 ACS Subarray Bias Calibration Program. Avoid SAA passages; SAA-impacted orbits are usable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 BIAS ACS/WFC ACCUM WFC1-2K DEF GAIN=2.0, COMPRESSION=NONE 6 0 S (0 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 1 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 2 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 3 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 4 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 5 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 6 none 1 N/A 14348( 5) - 29-Jul-2015 14:19:13 - [ 8] Visit: A2 Visit Requirements: On Hold Comments: Additional Comments: This internal orbit will be charged to the Cycle 22 ACS Subarray Bias Calibration Program. Avoid SAA passages; SAA-impacted orbits are usable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 BIAS ACS/WFC ACCUM WFC1-2K DEF GAIN=2.0, COMPRESSION=NONE 6 0 S (0 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 1 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 2 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 3 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 4 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 5 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 6 none 1 N/A 14348( 5) - 29-Jul-2015 14:19:13 - [ 9] Visit: A3 Visit Requirements: On Hold Comments: Additional Comments: This internal orbit will be charged to the Cycle 22 ACS Subarray Bias Calibration Program. Avoid SAA passages; SAA-impacted orbits are usable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 BIAS ACS/WFC ACCUM WFC1-2K DEF GAIN=2.0, COMPRESSION=NONE 6 0 S (0 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 1 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 2 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 3 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 4 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 5 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 6 none 1 N/A 14348( 5) - 29-Jul-2015 14:19:13 - [ 10] Visit: A4 Visit Requirements: GROUP A4, 01 WITHIN 14D On Hold Comments: Additional Comments: This internal orbit will be charged to the Cycle 22 ACS Subarray Bias Calibration Program. Avoid SAA passages; SAA-impacted orbits are usable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 BIAS ACS/WFC ACCUM WFC1-2K DEF GAIN=2.0, COMPRESSION=NONE 6 0 S (0 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 1 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 2 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 3 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 4 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 5 none 1 N/A BIAS 1 ACS/WFC ACCUM WFC1-2K DEF none none 6 none 1 N/A 14348( 5) - 29-Jul-2015 14:19:13 - [ 11] Summary Form for Proposal 14348 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1, WFC1-2K ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters COMPRESSION=NONE, GAIN=2.0 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP A4, 01 WITHIN 14D, PATTERN 1 1, PATTERN 1 2, PATTERN 1 3, PATTERN 1 4, PATTERN 1 5, PATTERN 1 6, PATTERN 1 7, PATTERN 1 8, PATTERN 1 9, SEQ A1, A2, A3, A4 WITHIN 1 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements DEF, F435W, F606W, F775W, POL0UV, POL0V, POL120UV, POL120V, POL60UV, POL60V ------------------------------------------------------------------------------------------------------------------------------------ Target Names ASASSN-2015LH, BIAS ------------------------------------------------------------------------------------------------------------------------------------